We address the problem of a swarm of autonomous
mobile robotic sensors generating geometric shapes
to build wireless ad hoc surveillance sensor networks.
Robot swarms with limited observation are required
to form different shapes under different task conditions.
To do this, we propose decentralized coordination
enabling a robot swarm dispersed across an area
to form a desired shape. Our approach has n robots
generate a circumscribed circle of a regular n-polygon
based on local interaction with neighboring robots.
The approach also enables a large robot swarm to
form concentric circles through consensus. We mathematically
demonstrate convergence confirming the
feasibility using extensive simulation. Our results indicate
that our approach is applicable to mobile sensor
network surveillance and security networks.